EP161 - Approach and Treatment Algorithm for Rectal adenocarcinoma in the setting of 2rd trimester pregnancy: Case Report

Saturday, May 9, 2026

3:25 PM - 3:30 PM ET

ePoster Presenter(s)

Vanessa Dlamini, MD (she/her/hers)

Resident Physician
University of Washington
UNIVERSITY OF WASHINGTON
Seattle, WA, United States

Disclosure information not submitted.

Author(s)

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dirir abdullahi, MD

Fellow
University of Washington
University of Washington
seattle, WA, United States

Disclosure information not submitted.
AA

Alexa T. Andre, MD

Resident
University of Washington
Seattle, Washington, United States

Disclosure information not submitted.
Mukta Krane, MD (she/her/hers)

Associate Professor of Surgery, Chief of Section of Colorectal Surgery
University of Washington
University of Washington Medicine
Seattle, WA, United States

Disclosure information not submitted.
BY

Betelhem Yohannes, MD

Resident
University of Washington
Seattle, Washington, United States

Disclosure information not submitted.

Senior Author(s)

Ragavan Siddharthan, MD

Assistant Professor
University of Washington
Seattle, WA, United States

Disclosure information not submitted.

Purpose/Background: Colorectal cancer is the second leading cause of cancer death in women younger than 50. These patients are not within typical screening guidelines, so it is essential that younger patients with irregular symptoms such as lower pelvic pain, changes in bowel habit, and bright red blood per rectum are evaluated. Unfortunately, all these symptoms can be associated with normal pregnancy potentially concealing a diagnosis of colorectal cancer. There are no defined guidelines related to colorectal cancer in the setting of pregnancy. This case report describes the presentation, diagnosis, and management of stage 3 rectal adenocarcinoma in the setting of pregnancy.

Methods/Interventions: The patient is a 35-year-old female who was diagnosed with rectal cancer during her second pregnancy after months of hematochezia. She experienced hematochezia with her first pregnancy but had a miscarriage in the first trimester after which her symptoms abated. She underwent a flexible sigmoidoscopy which showed a 5 cm mass at 10 cm from the anal verge. The mass was biopsied and confirmed a microsatellite stable rectal adenocarcinoma. Staging workup revealed a non-metastatic T3N1M0 mid rectal adenocarcinoma.

Treatment options including neoadjuvant therapy and primary surgical resection were discussed by a multidisciplinary team. The patient's goals were to have a viable pregnancy with as little harm to the fetus as possible. We decided upfront surgery, though technically feasible, would not be in line with the patient's goals given a high risk for miscarriage with manipulation of the uterus due to proximity of the cancer to the uterus (Figure 1) and anesthetic risks. Therefore, the patient underwent neoadjuvant chemotherapy with FOLFOX for 6 cycles. She subsequently underwent a C-section at 35-week gestation. Repeat staging showed increase size of the rectal mass. She therefore underwent chemoradiation to complete total neoadjuvant therapy (TNT). Prior to chemoradiation, the patient underwent ovarian transposition to decrease risk of future infertility. After TNT, restaging imaging showed decrease in the size of the mass and no persistent lymphadenopathy. Endoscopy showed a persistent mass with central necrosis. Intraoperatively, the mass was below the anterior peritoneal reflection and she underwent a robotic low anterior resection with complete total mesorectal excision and diverting loop ileostomy. Postoperative course was uncomplicated, and the patient was discharged home on postoperative day 4.

Results/Outcomes: The final pathology showed a 4.3 cm T3 tumor with 23 negative lymph nodes but 2 tumor deposits. The closest margin was the radial margin which was 1.2 cm (Figure 2).

Conclusion/Discussion: Colorectal cancer in pregnancy is rare with an incidence of less than 0.01% though, this number is expected to increase given the substantial increase in early onset colorectal cancer. Preventing misattribution of symptoms of colorectal cancer during pregnancy is key for early management by maintaining a high clinical suspicion. Each trimester of pregnancy carries specific risk with second and third trimester considered the safest for surgical or systemic therapy. Multidisciplinary approach to care is necessary for these patients and the psychosocial impact should be underscored with integration of supportive interventions for patients and families.

MRI pelvis w and wo contrast

Caption; MRI pelvis, thin blue arrow represents rectal mass, thick blue arrow represents fetus.
Histopathology

Histologic sections show residual adenocarcinoma (C) invading through the muscularis propria and into the pericolorectal tissue (A-B). Two separate tumor deposits were identified (D).